Coherent has redesigned the Chameleon OPO (Optical Parametric Oscillator) to provide simple access to tunable near-IR wavelengths for multiphoton excitation microscopy (MPE).
When used with any model of the Chameleon range of ultrafast lasers, this new OPO delivers continuous gap-free tuning from 1,000nm to more than 1600nm, with up to 600mW of specified output power.
Moreover, tuning causes no change in beam pointing direction and thus requires no adjustment of downstream (microscope) optics.
Chameleon OPO utilises a periodically poled crystal for which the poling is a function of the position in the crystal, forming a fan-shaped grating.
This not only yields efficient OPO wavelength conversion, but also enables the OPO to be pumped at any wavelength in the 740-880nm range.
The wavelengths of the Chameleon oscillator and the Chameleon OPO can thus be tuned completely independently, enabling simultaneous sample excitation at two wavelengths.
The tuning of both devices is controlled through a single common interface.
There are several advantages to using a tunable MPE source at longer (>1000 nm) wavelengths.
First, it enables optimum excitation of the new m-fruit fluorophores such as m-cherry.
In addition, these longer wavelengths are less damaging to live tissues, and also undergo less scatter, supporting deeper images.
Finally, the group velocity dispersion (GVD) of typical microscope optics is lower at these longer wavelengths, further enhancing MPE image quality.
